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Constant force mechanisms for regulating restriction devices

  • US 8,377,079 B2
  • Filed: 12/27/2007
  • Issued: 02/19/2013
  • Est. Priority Date: 12/27/2007
  • Status: Expired due to Fees
First Claim
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1. A self-regulating restriction system, comprising:

  • a restriction device for forming a restriction in a pathway;

    a pressure adjustment unit in communication with the restriction device and effective to maintain a substantially constant equilibrium pressure between the restriction device and the pressure adjustment unit by regulating an amount of fluid in the restriction device, the pressure adjustment unit having a housing with a constant force mechanism and an expandable bellows disposed therein, the expandable bellows being in fluid communication with the restriction device, and the constant force mechanism applying a constant force to the expandable bellows; and

    a set-point adjustment mechanism having an expandable bladder and a constant pressure spring, the set-point adjustment mechanism being aligned along a longitudinal axis with the pressure adjustment unit housing, the expandable bladder being inflatable to adjust the substantially constant equilibrium pressure, and the constant pressure spring being at least partially disposed around the expandable bladder.

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